Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

Jingfeng Wang; Zhenning Nie; Haiyan Chen; Xianhong Shu; Zhaohua Yang; Ruiming Yao; Yangang Su; Junbo Ge

doi:10.3791/56439

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Method Article

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

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DOI:

10.3791/56439

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December 11th, 2017

Jingfeng Wang^*¹ , Zhenning Nie^*¹ , Haiyan Chen^*² , Xianhong Shu² , Zhaohua Yang³ , Ruiming Yao¹ , Yangang Su¹ , Junbo Ge¹

¹Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, ²Department of Echocardiography, Shanghai Institute of Medical imaging, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, ³Department of Cardiac surgery, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University

^* These authors contributed equally

Summary

The establishment of a chronic asynchronous heart failure (HF) model by rapid pacing combined with left bundle branch ablation is presented. Two-dimensional speckle tracking imaging and aortic velocity time integral are applied to validate this stable HF model with left ventricular asynchrony and the benefits of cardiac resynchronization therapy.

Abstract

It is now well recognized that heart failure (HF) patients with left bundle branch block (LBBB) derive substantial clinical benefits from cardiac resynchronization therapy (CRT), and LBBB has become one of the important predictors for CRT response. The conventional tachypacing-induced HF model has several major limitations, including absence of stable LBBB and rapid reversal of left ventricular (LV) dysfunction after cessation of pacing. Hence, it is essential to establish an optimal model of chronic HF with isolated LBBB for studying CRT benefits. In the present study, a canine model of asynchronous HF induced by left bundle branch (LBB) ablation and 4 weeks of rapid right ventricular (RV) pacing is established. The RV and right atrial (RA) pacing electrodes via the jugular vein approach, together with an epicardial LV pacing electrode, were implanted for CRT performance. Presented here are the detailed protocols of radiofrequency (RF) catheter ablation, pacing leads implantation, and rapid pacing strategy. Intracardiac and surface electrograms during operation were also provided for a better understanding of LBB ablation. Two-dimensional speckle tracking imaging and aortic velocity time integral (aVTI) were acquired to validate the chronic stable HF model with LV asynchrony and CRT benefits. By coordinating ventricular activation and contraction, CRT uniformed the LV mechanical work and restored LV pump function, which was followed by reversal of LV dilation. Moreover, the histopathological study revealed a significant restoration of cardiomyocyte diameter and collagen volume fraction (CVF) after CRT performance, indicating a histologic and cellular reverse remodeling elicited by CRT. In this report, we described a feasible and valid method to develop a chronic asynchronous HF model, which was suitable for studying structural and biologic reverse remodeling following CRT.

Introduction

Advanced chronic HF is a leading cause of mortality for various cardiovascular diseases. A subset of patients with congestive heart failure (CHF) also develop ventricular conduction discoordination that aggravates symptoms and prognosis. CRT, also referred to as biventricular pacing, has been introduced as an alternative therapy for these patients for over 20 years¹^,². Unfortunately, about 20-40% of the patients show poor response to CRT. Since then, many studies have been carried out in order to maximize CRT response³. It is now well recognized that patients with LBBB could benefit mor....